OC 59.4 - Novel variants in GALE caused syndromic macrothrombocytopenia disrupting thrombopoiesis and glycosylation

Tuesday, July 12, 2022

11:30 AM – 11:45 AM

Location: ExCel Center, ICC Capital Suite Room 1

Presentation Format: In-Person

Presenting Author(s)

Ana Marin-Quilez, MSc

Postdoctoral researcher
Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, University of Murcia, IMIB, CIBERER-U765, Murcia, Spain
Murcia, Murcia, Spain

Co-Author(s)

CD

Christian A Di Buduo

Research Associate
Department of Molecular Medicine, University of Pavia, Pavia, Italy
Pavia, Lombardia, Italy
LD

Lorena Díaz-Ajenjo

Predoctoral researcher
Cancer Research Center - CSIC, University of Salamanca, Instituto de Investigación Biomédica de Salamanca (IBSAL), Spain
Salamanca, Castilla y Leon, Spain
PS

Paolo M Soprano

MSc
Department of Molecular Medicine, University of Pavia, Pavia, Italy
Pavía, Lombardia, Italy
EV

Elena Vuelta

MSc
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
IS

Inmaculada Serramito-Gómez

PhD
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
SS

Sandra Santos-Mínguez

MSc
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
CM

Cristina Miguel-García

BSc
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
ST

Silvia Tocino-Antonio

BSc
IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
Ana Zamora-Cánovas

Biotechnology
Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, Murcia, Spain.
Murcia, Murcia, Spain
PR

Pedro Ruiz-Sala

PhD
Centro de Diagnóstico de Enfermedades Moleculares, Universidad Autónoma de Madrid, CIBERER, IdIPAZ, Madrid, Spain
Madrid, Madrid, Spain
MP

María Jesús Peñarrubia

MD, PhD
Department of Hematology, Hospital Clínico Universitario de Valladolid, Spain
Valladolid, Castilla y Leon, Spain
EP

Emilia Pardal

MD, PhD
Department of Hematology, Hospital Virgen del Puerto, Plasencia, Spain
Plasencia, Extremadura, Spain
JH

Jesús María Hernández-Rivas

MD, PhD
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain; Department of Hematology, Complejo Asistencial Universitario de Salamanca (CAUSA), Instituto de Investigación Biomédica de Salamanca (IBSAL), Universidad de Salamanca (USAL), Spain
Salamanca, Castilla y Leon, Spain
JG

Jose Ramon Gonzalez Porras

Hematologo
Hospital Clínico Universitario Salamanca
salamanca, Castilla y Leon, Spain
RB

Rocío Benito

Postdoctoral researcher
Cancer Research Center - CSIC, University of Salamanca, Instituto de Investigación Biomédica de Salamanca (IBSAL), Spain
Salamanca, Castilla y Leon, Spain
José RIVERA Rivera, PhD

PhD
Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, Murcia, Spain
Murcia, Murcia, Spain
IG

Ignacio García-Tuñón

PhD
IBSAL, CIC, IBMCC, Universidad de Salamanca-CSIC, Salamanca, Spain
Salamanca, Castilla y Leon, Spain
Alessandra Balduini, MD

MD, PhD
University of Pavia, Pavia, Italy
Pavía, Lombardia, Italy
Jose Mª Bastida, PhD, MD

Hematology Department
Complejo Asistencial Universitario de Salamanca-IBSAL-USAL (Salamanca)
Salamanca, Castilla y Leon, Spain

Background: Glycosylation is recognized as a key process for proper megakaryopoiesis and platelet formation. The enzyme UDP-galactose-4-epimerase, encoded by GALE, is involved in protein glycosylation. There is currently scarce information about the performance of megakaryopoiesis in patients with thrombocytopenia associated with GALE variants.

Aims: Assessing the clinical and platelet phenotype in three patients with syndromic macrothrombocytopenia associated to GALE variants, and to investigate the role of GALE in glycosylation and thrombopoiesis.

Methods: Three patients from two unrelated families with lifelong severe thrombocytopenia, bleeding diathesis, mental retardation, mitral valve prolapse, and jaundice were enrolled in the Spanish Project of Inherited Platelet Disorders. Biallelic variants in GALE were identified by whole-exome sequencing (WES) (Figure 1). Platelet phenotyping included full blood cells count, blood film, light transmission aggregometry, flow cytometry analysis of major surface platetet glycoproteins, and agonist-induced granule secretion. UDP-galactose-4-epimerase enzymatic activity was measured by HPLC/MS/MS. GALE and N-acetyl-galactosamine (LacNac) levels were evaluated by immunoblotting. Human megakaryocyte (Mk) culture from peripheral blood samples was assessed in one proband.

Results: WES revealed four variants affecting GALE, three of them previously unreported (Figure 1). Patients showed giant and grey platelets, impaired platelet aggregation with several agonists and severely reduced alpha (P-selectin) and dense granule (CD63) secretion. UDP-galactose-4-epimerase enzymatic activity was severely decreased in these patients. Immunoblotting showed reduced GALE in platelets and significant reduction of LacNAc, suggesting a hypoglycosylation pattern. In proband B.II.2, CD34+ derived Mks exhibited normal ploidy, and maturation, but impaired proplatelet formation. These Mks showed, similarly to patient platelets, normal surface levels of β3 integrin, but remarkable reduction in the externalization of GPIbα.

Conclusion(s): This study expands our knowledge on the GALE related thrombocytopenic disorder, emphasizing its critical role in platelet glycosylation, and providing further evidence that thrombocytopenia derives from altered proplatelet formation developing from GPIbα impairment.

Funding: PI20/00926, GRS2135/A/2020, GRS2314/A/2021, FMM AP172142019.